Frequency multiplier



June 27,1944. H, R'SUMMERHYES, JR' 2,352455 FREQUENCY MULTIPLIER FiledSept.. 3 0. 1943 Q a Tm oe vm. @mdp QU. v5 A TmR .Mw WH m H w eines-ibacri tai accetta-'iai Patented June 27, 1944 i `assigner to GeneralElectric Companygfa'corl por-atonoftN'ew York e Application september30, 1943,. serial.. 5043er/ My' intender-relates to.. frequencymultipliers and ilfiorei Daltililarltf @apparatus-.ier obtainingfrequency multiplication .and ampliiieatiori--; by

utilizing ielatirely low; frequency crystal osenlators. f

Clr

it; isfarn.- object; ofii multiplier;

iniptei'fed .arrangement ,for maintaining stable. i

Oneratien 0f.. thef.f.m111tii21ierf, with yrelativelylcwf crystalexcitation.; Y j K, It ancthercbieatzei my inifeiiticn-.to-nroride.A a.frequency multiplier-minimising anl ainnliner: aiidircneiict tripler-.ircuits and.: anrecieved arrangement-ier .diritta feedback of enerexatgthe desiredi ii for increasinrtneeute- Ptit i.nteneiitrrt while.maintaiiiins the. required. low crystal e2'z` ':'tationy necessary toIinsureL-'stablej op@ eration.

i The ffeatures of myinvention Whichgl AAbelieve' tibip novell aresetvforthwith'particularityiir thfaPDendedclaim-1s.Y A y ever, both. asto itsorganization and# method" of operation, together withfurther'ebiectseandeada vamagesthereof., may vilcestoe understood ref--AMy invention 'itsel-fj hour-.i 3

erenceto .the followingdescription Vtakei'i'eih vcon'-4 nection with.-the accompanying-drawingein'Which- Fig. 1diagrammaticallyfrepresenta-one formv of frequency inuitiiilierAvcircuit; embodying.: ve. ien; .Fiefsiiand re'riresent equivalent ein..vCit diaerame;e'fltlie .uitshownin Fie., 15, and` Fi'iiisa. Yee'tcr diag'lius'trating merope. atieiipfniepireuirg l Referring iiQW to .Eeifhthe. frequencyi inultif..

pilier 'circuit hasbeenllliistrated asrafhar multiplier' of a' generaltpefwei'ilrnpn: in,` art Ari electron discharge; device,- 10; having: an

mais resister. l.; 'o l1.111, the output@ :f 0`between the anode I I4and the 55 cathode I3 therefare;connected a parallel circuit I6comprising an inductance I1 and a condenserv I-8,-a.p.ara11elcircuiti-2in' comprisingan.inductance ZI;` and nga. condenser. 2 2; and:ai suitable battery or other; source, ofc direct :.current.. potential;mi Thegfirst. Circuit |161.' is .-tunedi to 1 afrequency above but;near. thee natural;.frequencyP ot .the crystal and the; secondttuned lcircuit 20. which. consti@v tntesmhe harmonicy multiplier. 'istpreferably tuned tog'aneodd; `harmonic.4 of. the; fundamentarfre--Vquency.; If the. circuit.l .tiwere .tuned to:` a.. ire'a quencyi very;near` the natural frequencyv ofthe crystal; :tofzobtairr .urna-Ximum.youtput, ouereexcita.-

tionandiiuj-um orgdestructinnoffthecrystaltmight result and stable;.operationi-y the; requiredl treqmncy .Wouldehe impossible;. Ittisi forthis rea-A "lia .the circuit..|36; isznotf.tuneditdproiride buteisftunedtoiarequencyi suf'-k iiciently ahoyeithematurat' frequenciesothattheexciiiatiorrof: theecrystale is@ reduced and? stable @eration insurcda.'.'ihtr` propere: adjustment. of this?. itx-Def 'or clioutandi the`rmarinergirr lwhich. it Operates; areg :Welk krimi-Z111 im theiart.::'Ihe. grid. mail@ .llcsistoie .andrtljre-.capacii;iles: associatedthere.. withtioigierraimple; ,thehcapacitw of; the crystalanriftlie-gridrtmcathode .capacity yofcthe .device,y 1.0i

aim-selected.so.ithatiainegatiuezbias existsom thev glidi.. lill fantilQllalyniimstivervoltage: peaks.- cause 1 anodefcurrentit 4flows; .tnef.ware fform; of; the theretorexri'chfin harmonics Ei`SJircutiiZsQsQiHa-tesc at.- the.. multiple Adamen-tai. lfrequency tol-whicimi-i; lis t fW''; hefllnderstood .thatgtha tumngot the circuitsf-Itandem depends notonlw emthe apacitieszothe .condenserse l;8;;.an`d,22leutz also Qltfthsctlzicranigaities y'which arejnherently preseI ent,Lth. destine,-l..ll;;;- 1t nature; .voltaefaapnearine across: thellffiszconnled; to; .theeinput .circuit-:ot an electron dischargedevice'shaying'ianc anode. Zei-...a contratel.entr-cdc;1zii:anni.areathoclev 2e; .the eircuitz21l-beingicounleiirthe griet zsftmoughia Smde reirsfnce .28'.1... .A tunedf; cir:-

ge 2111i iliidiltance.- 33|) 'andzas vara-i aiconnectediirrzloaralleilis corr-i netted thema-tent circnitnirtne deyieeiiaztef... iwlritalli851:10@ @,alldgthes Cathode; Zizin; series Watters.: 33;. circuit; l3i)isi .tunect Reefer,abi-y;rv tol `ani oddi harmonic: of:` .the-Lfrequency offV .theecircniti 211,: fori. examp1e-,. the: thirdil har-fmonic. The; timel constant ortheeresis'tanceaanda Qaicitycfcombnation.,comprising lthe re'sistarliccL 28 and capacitance 21 is chosen so thata negaof the apparatus through a suitable coupling condenser 34. Thedevices I and 23 thus perform the functions of an oscillator, anamplifier and a frequency multiplier. M Because .ofthenecessityf ofmaintaining relativelyff 10W excitation of the crystal the highfrequency energy available at the output of the multiplier must berelatively lowvx provided stable operation is to be obtained. The

high frequency output of the tube -23 r'nay-beil increased by feedingback energy ,from itsoute put circuit to its input circuit,`andI.'liavefound' that this may be accompusiied efliciruywith a minimumnumber of additional circuit elements by employing an inductancef35connectedin sel'- A greatly ".Ili-L..

ries with the control grid 25.

creased high frequency output may be obtained by the circuit whenprovidedfrwitnithis induct i The manner in :which: theninductance35t'op-l eratesto provide the feedbackcf :energy atthefrequency of. thecircuit l3|) may treadily `beunder stcodtfrom the equivalent circuitdiagrams of Figs.

2 and3 and the vector: diagram of Fig. 4.; `In Fig.l 2t the impedance ofallsthecomponents of the circuit ofFigl lWhichy are'connected betweenIthe input'of the impedance 35 and ground have been represented by acapacitor 3l.' .c Fig. 2` is. drawn withlreference -to thethighfrequency appearing across theoutput circuit and'the-circuitsil and y20which aretuned tomuchlowerfrequem' cies. present a capacitiveYreactanceiat the-high frequencies; this' assumptionlneglects theresist:- ance losses which arel relatively unimportant. The. impedanceof. the "devices I 0 is also essentiallya. capacitive reactance. inparalleliwith -a AAhigh resistance.. tAllithese. capacitive reactanceskhave beencombined and represented by' the capacitor- 3l.I y .Thecapacity indicated` in 'dottedlines atl-38 represents the Janodetogridi'capacityof the de-f vice l23 and: capacities betweenstheassociated` leads. The inductance v'is selecteditorhavea value such thatf whenf it=.is; combined in series Withithe condenser 3`|vtheresultant-'reactancewilll berinductive andof theorderfofone-twentieth-of the reactance of theV gridl tocathodef capacitylof a voltage Eg' is developed bythe current Ig across the inductance 40and leads the current by 90; the voltage Eg' therefore is 180 out ofphase with Ep. Since the parallel circuit 30, taking into account theother impedances associated therewith in the anode circuit, is tuned toresonance, it pre- 'sents a resistive impedance to the voltage Ep, andEp is, therefore, 180 out of phase with Eg. The voltage Eg andthefeedbaclcyoltageyEgf'are thereforel'in i` h a's"e,fwhich is thecbndition'required for regeneration. It will be found that as the effectiveinductive reactance 40 is increased as by inwcreasisng the inductatice35, the feedback of energy y"-f-rr'n 'the output to the input of thedevice 23 is i increaseduntil a value of the inductive reactancereacl'ifedatWhifch self-oscillation of the cir- .Occurs It ist ofcourse, desirable to avoid self-oscillation and for this reason a valueof inductive'-reactanceless` than that which produces self :oscillationis selected. The increase in output produced by a value of inductivereactance below the value for. self-oscillationl isls'tillV verysubstantiall and? .makes it possible A to operate the circuit withI`the' ifr'elatively: ilow excitationL 'of the crystal which is necessaryto insure frequency stability. Greatly increased output at the highharmonicv frequency may thus be obtained. *if y It will beeVident/thatmyl invention provides a structurally simple and *effective "frequencymultiplying circuit-with a minimum -number of circuit components. Byproper selection 'of theV feedback impedance 35,- high efficiency `v`andjsta- I bilityv .are attained'l togetherf-With amplification I Withoutthe rnecessity 'ofl increasing'f the crystal excitation.' *By Wayofillu'strationcnly, and' not i by way of limitation,f-there'arelistedbelow values of vcircuit constants which' have been found-"toibesuitable foi-'the circuit Aof" Fig. 1 when employed in--azparticularfrequency multiplier in which the harmonic circuitsV 20 'and 30lWere'tuned to" the third -Il.ia'r-monic fof thefunda'mental frequencyand -tlffe frequency ofthel circuit 20, "respecthedevice23lindicatedat39m Furthermore,

combination. circuitl comprising'l the in'ductanc'ez and icondenser, 31in series yshunted"byf'thej cathode capacity 39 has an; effectiveJinductive reactance which maybe representedby'arix iii-Jy ductance 40,as indicated-in Fig. 3-. Furthermore; since the grid. to` plate and y1the grip-to cathodel capacities of a threeeelement tube,'lls`ruchrlasthedevice 23, are always of the same order of lmagni-f tude, theinductive reactance 40 ofthe-order of one-twentieth the:capacitive;-reacta'ncer ofithe plate togrid capacity 38.

- yThel vector l`relationships ofi the? voltages and currentsinFig. 3are indicated-in Fig. 1r-these vectors. are shown 'with -respecteto'rtheir relative' phase .relationshipbutnotlfnecessa'rily jwith -rel spectto theirmagnitudes. `'The-'vector E'psrep'revsents the;anode .voltagecfthe-'device' 23.

voltagecauses a current representedby the-vector- Ig; to flow throughAthe seriescircuit'includingfthe capacity38 and-the effectiveinductance-lllt).Y The current Ig leads the voltagerEp by`90 becausetheL branch .of the. anode-:cathodeA impedance: lcon-t sisting ofthe'capacity'38 and inductance-dinf serieshas an effectivecapacitiverreactancey," andlWhat 'I claim as" new' 22 were 5 to 25 Mtfd. air trin'inier p'acitors 'ha ysatisfactoryv value-vof the`inductance'35f':was "foundto` beV ap'p`rd'nximatelyI 0.41-micrcheriry.The crystal @oscillator frequency was17i372megacyclesi The directcurrent potential pfthe'sources 9 and'33 an input circuit tuned to afundamental frequency and connected between said cathode and saidcontrol electrode, an output circuit tuned to a harmonic of thefundamental frequency and connected between said anode and said cathode,said input circuit being capacitive at said harmonic frequency, meansproviding a negative bias for said control electrode whereby onlypositive wake peaks at said fundamental frequency render said deviceconducting, and an inductance connected in series between said controlelectrode and said tuned input circuit for providing regen-` erativefeedback of energy at said harmonic frequency.

2. A frequency multiplying apparatus comprising a crystal oscillator, acircuit in the output of said oscillator tuned to a predeterminedfrequency, an amplifier comprising an electron discharge device havingan anode and a cathode and a control electrode, the control electrode tocathode circuit of said amplifier being connected to include said tunedcircuit, an output circuit for said amplifier connected between saidanode and said cathode and tuned to a harmonic of the frequency of saidrst mentioned tuned circuit, the input circuit of said amplifier beingcapacitive at the frequency to which the output circuit thereof istuned, means providing a negative bias for said control electrodewhereby only positive wave peaks at the frequency of said firstmentioned tuned circuit render said device conducting, and an.-inducta'ncel connected in series between said control electrode and saidfirst tuned circuit for providing a regenerative feedback of energy atsaid harmonic frequency.

3. A frequency multiplying apparatus comprising a crystal oscillatorvincluding an electron discharge device having a piezoelectric crystalconnected in the input circuit thereof, and a. first circuit tuned tothe fundamental frequency of the crystal connected in the output circuitthereof, a second tuned circuit connected in the. output of said deviceand ltuned to a harmonic of said fundamental frequency, an amplifiercomprising an electron discharge device having an anode and a cathodeand a control electrode, the control electrode to cathode circuit ofsaid amplifierbeing connected to include said second tuned circuit,an-output circuit for said amplifier connected between said anode andsaid cathode and tuned to a harmonic 'of the frequency of said secondtuned circuit, said second tuned circuit being capacitive at thefrequency to which said output circuit is tuned, means providing anegative bias'for said control electrode whereby only positive wavepeaks at the frequency of said

